<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <div id="app">
        <p>{{counter}}</p>
    </div>
    <script src="https://cdn.jsdelivr.net/npm/vue@2"></script>
    <script>
        //创建的是app的实例，
        const app = new Vue({
            el: "#app",
            data: { counter: 1 },
        })
        setInterval(() => {
            app.counter++
        }, 1000);
    </script>
</body>

</html>